Apparatus for securing a spinal rod system

ABSTRACT

An apparatus for securing a spinal rod within an anchoring device, wherein the anchoring device has an open end and a locking cap for securing the spinal rod within the open end. The apparatus includes a handle, an elongated body connected to the handle, a pair of jaws attached to the elongated body, a rod persuader for advancing the rod toward the anchoring device, and a locking shaft for use in locking the locking cap against the anchoring device to secure the spinal rod relative to the anchoring device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/441,764, filed on May 20, 2003, which is based on U.S. ProvisionalApplication No. 60/385,994 filed on Jun. 4, 2002, the teachings of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a surgical instrument and, moreparticularly, to an apparatus and method for securing a spinal rodsystem.

The spinal column is a complex system of bones and connective tissuewhich protects critical elements of the nervous system. Despite thesecomplexities, the spine is a highly flexible structure, capable of ahigh degree of curvature and twist through a wide range of motion.

For many years, orthopedic surgeons have attempted to correct spinalirregularities and restore stability to traumatized areas of the spinethrough immobilization. Over the past ten years, spinal implant systemshave been developed to achieve immobilization. Such systems ofteninclude spinal instrumentation having connective structures such aselongated rods which are placed on opposite sides of the portion of thespinal column intended to be immobilized. Screws and hooks are commonlyutilized to facilitate segmental attachment of such connectivestructures to the posterior surfaces of the spinal laminae, through thepedicles, and into the vertebral bodies. These components provide thenecessary stability both in tension and compression to achieveimmobilization.

Accordingly, the subject disclosure is directed to an apparatus tofacilitate securement of the screws and hooks to the connectivestructures of a spinal stabilization system. Specifically, the apparatusis used in connection with a spinal rod system and assists inpositioning the rods of the system relative to the spinal screws andsecuring the system at a desired orientation.

SUMMARY OF THE INVENTION

An apparatus for facilitating securing of a spinal rod within ananchoring device having an open end and a locking cap for securing thespinal rod within the open end, includes:

a handle

an elongated body connected to the handle and defining a longitudinalaxis;

a pair of jaws mountable to the elongated body, the jaws adapted forrelative movement between an open displaced position and a closedposition, the jaws defining structure for engaging the anchoring devicewhen in the closed position thereof;

a rod persuader at least partially disposed within the elongated bodyand adapted for longitudinal movement therein, the rod persuaderadvanceable within the elongated body to operatively engage the spinalrod to approximate the spinal rod with respect to the open end of theanchoring device; and

a locking shaft disposed within the elongated body and operativelyengageable with the locking cap of the anchoring device, the lockingshaft movable relative to the elongated body to move the locking cap toa secured position thereof within the anchoring device to secure thespinal rod relative to the anchoring device.

The rod persuader includes mounting structure for releasably mountingthe locking cap such that the locking cap engages the spinal rod uponadvancing movement of the rod persuader. The locking shaft may beoperatively engageable with the rod persuader upon movement of the rodpersuader to an advanced position thereof wherein movement of thelocking shaft causes corresponding movement of the locking capreleasably engaged to the rod persuader. The locking shaft may beadapted for rotational movement to move the locking cap of the anchoringdevice to the secured position thereof.

The jaws each include detents for releasably engaging correspondingstructure of the anchoring device. The jaws may be spring-biased to theopen position thereof. One of the jaws is preferably a stationary jaw infixed relation to the elongated body and the other of the jaws is amovable jaw. A manually engageable lever is connected to the movablejaw. The lever may be movable to cause corresponding movement of themovable jaw between the open and closed position of the jaws. A lockoutmechanism including a lockout arm engageable with the manuallyengageable lever may selectively secure the movable jaw in the closedposition.

The locking shaft is adapted for rotational movement to move the lockingcap to the secured position thereof. The locking shaft is adapted tooperatively engage the locking cap upon advancing movement of the rodpersuader a predetermined distance thereof whereby rotational movementof the locking shaft causes corresponding rotational movement of thelocking cap. The locking shaft define a central lumen therethrough forreception of the rod persuader and the rod persuader is adapted forlongitudinal movement within the locking shaft.

The locking shaft includes a keyed recess dimensioned to receivecorresponding keyed structured of the rod persuader whereby rotationalmovement of the locking shaft causes corresponding rotational movementof the locking cap. The rod persuader may include a proximal rod portionand a distal rod portion. The proximal rod portion is adapted to rotaterelative to the distal rod portion adapted for relative rotationalmovement. With this arrangement, the distal rod portion includes thekeyed structure.

Alternatively, the rod persuader may be operatively engageable with thelocking shaft such that upon movement of the rod persuader to thepredetermined position thereof rotational movement of the rod persuadercauses corresponding rotational movement of the locking shaft andlocking cap to the secured position thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentinvention and, together with the general description given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the present invention.

FIG. 1 is a front perspective view of the apparatus for securing aspinal rod system in accordance with the present invention;

FIG. 1A is an enlarged view of the area 1A-1A of FIG. 1;

FIG. 2 is an exploded view of the apparatus with parts separated;

FIG. 3 is a side elevational view of the apparatus of FIG. 2;

FIG. 4 is a rear perspective view of the apparatus of FIG. 1;

FIG. 5 is a side cross-sectional view of the apparatus with the jawmechanism closed;

FIG. 5A is a cross-sectional view taken along the lines 5A-5A of FIG. 5;

FIG. 6 is an exploded view of the locking shaft of the apparatus;

FIG. 7 is a cross-sectional view of a handle assembly of the lockingshaft;

FIG. 8 is a perspective view of a handle housing of the handle assemblyshown in FIG. 7;

FIG. 9 is an axial view of the tubular body;

FIG. 10 is a perspective view of the rod persuader of the apparatus;

FIG. 11 is a perspective view of a cap spin of the rod persuader;

FIG. 12 is an exploded view with parts separated of the rod persuader;

FIG. 13 is a cross-sectional view of the cap spin;

FIG. 14 is an exploded view of a pedicle screw;

FIG. 15 is an enlarged perspective view of area “X” of FIG. 14,illustrating the head of the pedicle screw;

FIG. 16 is an exploded view of a cap of the pedicle screw as seen frombelow;

FIG. 17 is a perspective view of the assembled cap of the pedicle screwas seen from below;

FIG. 18 is a cross-sectional view of the apparatus with the jawmechanism in the open position;

FIGS. 19A-19B are cross-sectional views of the apparatus with the rodpersuader advanced for mounting the locking cap of the spinal rodsystem;

FIG. 20 is a side cross-sectional view of the apparatus of FIG. 1, shownmounted on to the head of the pedicle screw;

FIG. 21 is an enlarged view of area “21” of FIG. 21;

FIG. 22 is a cross-sectional view of the apparatus taken at “22-22” ofFIG. 20;

FIG. 23 is a side cross-sectional view of the apparatus illustrating thepositioning of a rod in the head of the pedicle screw;

FIG. 24 is an enlarged view of area “24” of FIG. 23;

FIG. 25 is a side cross-sectional view of the apparatus illustrating thelocking of the cap of the pedicle screw to the head of the pediclescrew;

FIG. 26 is an enlarged view of area “26” of FIG. 25;

FIGS. 27A-27B illustrate release of the rod persuader from the lockingcap of the pedicle screw;

FIG. 27C is an enlarged view illustrating the opening of the jawmechanism; and

FIG. 28 is a perspective view of a pair of pedicle screws secured to avertebral body and having a rod extending through the pair of pediclescrews.

DETAILED DESCRIPTION

Preferred embodiments of the apparatus for securing a spinal rod systemwill now be described in detail with reference to the drawing figureswherein like reference numerals identify similar or identical elements.In the drawings and in the description which follows, the term“proximal,” as is traditional, will refer to the end of the apparatusclosest to the operator, while the term “distal” will refer to the endof the device or instrument furthest from the operator.

Apparatus 100 is adapted for use with a spinal rod system to facilitatemanipulation and securement of the rod system relative to the spine ofthe patient. It is envisioned that apparatus 100 may be suited for avariety of spinal rod systems which incorporate an open ended pediclescrew and a locking member positionable in the screw end for lockingengagement with the rod or the screw head. Apparatus 100 is particularlyadapted for use with the spinal rod system disclosed in commonlyassigned application Ser. No. 09/487,942, filed Jan. 19, 2000, thecontents of which are incorporated herein by reference. The spinal rodsystem disclosed in the '942 application will be described in furtherdetail hereinbelow.

Referring initially to FIG. 1, the apparatus in accordance with thepresent disclosure, is shown generally as reference numeral 100.Apparatus 100 includes several mechanisms, namely, rod persuader 102,locking shaft 104 and jaw mechanism 106. Generally, rod persuader 102functions in engaging a spinal rod of a spinal rod system andmanipulating the rod into an open recess of the screw head. Lockingshaft 104 secures the locking member of the spinal system within theopen pedicle screw head. Jaw mechanism 106 mounts to the pedicle screwto stabilize the apparatus 100 relative to the spinal rod system duringoperation of the apparatus 100.

With reference to FIGS. 2-5 in conjunction with FIG. 1, jaw mechanism106 will be initially discussed. In FIGS. 3-5, rod persuader 102 isshown removed from the apparatus 100. Jaw mechanism 106 includes tubularbody 108 coaxially arranged about both rod persuader 102 and lockingshaft 104. Tubular body 108 defines an enlarged flange 110 at itsproximal end and collar 112 coaxially mounted about the tubular body 108adjacent the flange 110. Tubular body 108 has fixed jaw 112 and movablejaw 114 pivotally mounted to the fixed jaw 112. Fixed jaw 112 includesproximal tubular sleeve 116 which is received within the lumen oftubular body 108 and a pair of spaced apart side walls 118 extendingfrom the tubular sleeve 116. Fixed jaw member 112 has a region ofreduced thickness and includes a tooth 120 projecting from the surfacethereof. Tooth 120 defines an elongated circle or racetrack-shapedconfiguration having a pair of flattened opposed sides; however, it isenvisioned that tooth 120 can take any shape and/or configuration.

Movable jaw 114 is pivotally mounted to fixed jaw 112 through pivot pin122 extending through corresponding pivot holes 124, 126 of the movablejaw 114 and fixed jaw 112, respectively. Movable jaw 114 defines aclevis 128 at its proximal end. Clevis 128 has a through bore 130 forreceiving connecting pin 132. Movable jaw 114 further defines tooth 134at its distal end in diametrical opposed relation to tooth 120 ofmovable jaw 114. Tooth 134 is substantially identical in configurationto tooth 120 of fixed jaw 112. Tooth 134 is best depicted in FIG. 1A.

With continued reference to FIGS. 2-5, jaw mechanism 106 furtherincludes lever 136 which is adapted for pivotal movement to causecorresponding pivotal movement of movable jaw 114. Lever 136 defines adistal region 138 which is received within side walls 118 of fixed jaw112. Distal region 138 defines a through hole 140 which receivesconnection pin 132 to connect lever 136 to movable jaw 114. Distalregion 138 further includes a proximal through hole 142 which receives apivot pin 144 extending through pivot holes 146 of stationary or fixedjaw 112. Lever 136 pivots about pivot pin 144 to move movable jaw 114between the open and closed positions.

With continued reference to FIGS. 3-5 in conjunction with FIG. 2,apparatus 100 further includes contoured handle 148. Handle 148 definesa semi-circular inner surface 150 correspondingly dimensioned tocooperate with the outer surface of tubular body 108. Handle 148includes a pair of spaced apart walls 152 extending from circular innersurface 150. Walls 152 include a first pair of holes 154 which receivepin 156. Pin 156 is accommodated within an arcuate recess 158 formed inan outer surface 110 of the tubular body to thereby axially androtatably fix tubular body 108 relative to handle 148.

Handle 148 further includes rack 160 pivotally connected to handle 148through pivot pin 162. Rack 162 has a plurality of ratchet teeth 164adapted to cooperate with proximal tooth 166 of lever 136 to selectivelysecure the lever 136 and thus move movable jaw 114 at desired positionsbetween the open and closed positions thereof.

As best depicted in FIGS. 2 and 5, apparatus 100 further includes a leafspring 168 connected to the outer surface of tubular body 108 byfasteners 170. Leaf spring 168 includes resilient proximal and distalfree ends 172, 174. Proximal and distal free ends 172, 174 are adaptedto engage respective recesses 176, 178 formed in rack 160 and lever 136.Accordingly, with this arrangement, leaf spring 168 functions to bothbias the rack 160 into engagement with lever 136 and bias lever 136towards a position corresponding to a closed position of movable jaw114.

Referring now to FIGS. 6-8, in conjunction with FIGS. 2 and 5, lockingshaft 104 will now be discussed. Locking shaft 104 includes severalcomponents operatively connected to each other, namely, from proximal todistal, handle 180, connecting sleeve 182 partially disposed within thehandle 180, main body 184 and socket 186 connected to the main body 184.Handle 180 has a cylindrical housing 188 and a pair of diametricallyopposed handles 190 (FIG. 6) extending radially from the housing 188.Handle assembly 180 includes through bore 191 extending centrallytherethrough and an annular rim 192 integrally formed in a distalsurface thereof. Preferably, annular rim 192 is spaced a distance from aterminal edge of the distal surface of housing 188. Housing 188 furtherincludes an off-axis through axial bore 194.

A dowel 196 is received within axial bore 194 and projects from thedistal surface of housing 188 for reception within a recess 198 definedin the proximal surface or flange 110 of tubular body 108. FIG. 9 is anaxial view of the configuration of recess 198 of tubular body 108. Asshown, the recess 198 extends through an arc of about 45 degreesrelative to the axis of the tubular body. Thus, handle 180 is capable ofrotation relative to the tubular body 108 through an angle equal to thearc of recess 198 of flange 110, i.e., 45 degrees. Other angularrecesses are envisioned as well. Bearing 200 is provided to facilitaterotational movement of handle 180 (FIG. 7).

Connecting sleeve 182 of locking shaft 104 is mounted about the proximalend of main body 184 and secured thereto via an interference fit orother conventional means. Connecting sleeve 182 is securely mountedwithin bore 191 of handle 180 and defines an internal thread 202 (FIG.5). Socket 186 of locking shaft 104 is partially mounted about main body184. Socket 186 defines an internal opening or keyed structure 205having a racetrack configuration as depicted in the cross-sectional viewof FIG. 5A.

Referring now to FIGS. 10-13, in conjunction with FIGS. 1-2, rodpersuader 102 will be discussed in detail. Rod persuader 102 includesrod shaft 204 having handle 206 mounted at its proximal end and cap spin208 coupled to its distal end. Rod shaft 204 includes a helical thread210 adjacent its proximal end. Helical thread 210 is adapted to engageinternal helical thread 202 of connecting sleeve 182 whereby rotationalmovement of the rod shaft 204 causes the shaft 204 to axially translate.Cap spin 208 includes a shaped tip 212 for engaging a rear end of alocking cap of the spinal rod system as will be discussed. As seen inFIG. 11, shaped tip 212 has a torx configuration, however, alternativeconfigurations may also be utilized to facilitate axial rotation of thelocking cap, such as, for example, cruciform, polygonal, hexagonal, etc.In addition, cap spin 208 includes a pair of opposed planar surfaces 214to define a cross-section of the cap spin 208 which corresponds forreception within keyed opening 202 of socket 186 upon advancement of rodshaft 204 a predetermined distance.

With reference to FIG. 12, handle 206 includes a through bore 216 sizedand shaped to receive the proximal end of rod shaft 204 therein.Preferably, handle 206 includes a threaded opening 218 which is formedtransverse to bore 216 and receives a lock screw 220 for engaging theouter surface of rod shaft 204 and thus prevents handle 206 fromseparating from rod shaft 204. Cap spin 208 is rotatably mounted to rodshaft 204 through a slip fit connection effected by circumferentialrecess 222 of the cap spin 208 and slip pin or bearing 224 extendedthrough a bore in rod shaft 204 and received within the recess 222.

Referring now to FIGS. 14-17, the spinal rod system intended for usewith instrument 100 is illustrated in detail. As discussed hereinabove,this system is disclosed in commonly assigned application Ser. No.09/487,942. Spinal rod system 400 includes an elongated spinal rod 402having a circular cross-section and a substantially smooth outer surfacefinish. As illustrated, anchoring devices in the form of bone screws 404are provided for securing spinal rod 402 to the spine during a spinalstabilization procedure.

With continuing reference to FIGS. 14-17, and in particular to FIGS. 14and 15, bone screw 404 includes a head portion 406 defining a horizontaland a vertical axis. A shank portion 408 depends from head portion 406and a threaded portion 410 having a helical thread 412 extending aboutthe outer periphery depends from shank portion 408. Helical thread 412is particularly adapted to securely engage the vertebral bodies of thespine. Head portion 406 defines a substantially U-shaped channel 414,formed along the horizontal axis thereof, for receiving spinal rod 402.In particular, U-shaped channel 414 is defined by the interior surfacesof side walls 416 and 418 and curved lower wall 420, which extendstherebetween. Head portion 406 further includes an elongated slot 423formed in each side wall 416, 418. It is envisioned that slots 423 areconfigured and adapted to receive tooth 120 of fixed jaw member 122 andtooth 146 of movable jaw member 124.

Bone screw 404 includes a locking cap 430 having an upper portion 432and a lower portion 434. Upper portion 432 includes a substantiallycylindrical cap body 436 defining an axial reception port 438 forreceiving and cooperating with shaped tip 212 of cap spin 208 of rodpersuader 102. Upper portion 432 further includes a pair ofcircumferentially opposed arcuate engagement flanges 440, 442 whichextend radially outward from cap body 436. Engagement flanges 440, 442include oppositely inclined, radially inward sloping, camming surfacesfor cooperating with a corresponding complimentary inner opposed arcuateengagement slot 422, 424 formed in opposed side walls 416, 418 of headportion 406. Flanges 440, 442 of locking cap 430 become engaged incorresponding slots 422, 424 upon rotation of upper portion 432 oflocking cap 430 relative to head portion 406 of bone screw 404.

Lower portion 434 of locking cap 430 is configured and adapted forcooperative reception within U-shaped channel 414 of head portion 406and is adapted to engage spinal rod 402 extending through U-shapedchannel 414. More particularly, lower portion 434 has a curved exteriorsurface which compliments the interior curvature of side walls 416, 418of had portion 406. Lower portion 434 of locking cap 430 is providedwith a hemi-cylindrical channel 444 formed in an undersurface thereoffor engaging and cooperating with spinal rod 402 upon loading of lockingcap 430 in U-shaped channel 414. Lower portion 434 includes a radiallyextending flange 446 which aides in the alignment and positioning oflower portion 434 with respect to spinal rod 402.

As been seen in FIG. 16, the lower surface of upper portion 432 oflocking cap 430 includes a recessed seating area 448 and an associatedaxial reception bore 450. Recessed seating area 448 is configured anddimensioned to accommodate lower portion 434, while reception bore 450is configured and dimensioned to receive and engage an axial post 452which projects from an upper surface 454 of lower portion 434 of lockingcap 430. The interaction of axial post 454 and axial reception bore 450facilitates relative rotational movement of upper portion 432 relativeto lower portion 434 when locking cap 430 is loaded into and locked inhead portion 406 of bone screw 404 during a spinal stabilizationprocedure.

Use of a two-part locking cap enables a surgeon to load locking cap 430into U-shaped channel 414 and properly position lower portion 434against spinal rod 402 so as to ensure a tight engagement betweenhemi-cylindrical channel 444 and the cylindrical surface of the spinalrod. Thereafter, upper portion 432 may be rotated into a locked positionrelative to lower portion 434.

During a spinal stabilization procedure, bone screws 404 are firstimplanted into the vertebral bodies of the spine and spinal rods 402 arethen fitted into U-shaped channels 414 of each bone screw 404. Once bonescrews 404 are in place and spinal rod 402 seated within U-shapedchannels 414, locking caps 430 are loaded into head portion 406. At sucha time, hemi-cylindrical channel 444 of lower portion 434 will engagethe cylindrical surface of spinal rod 402 and be maintained in a fixedaxial orientation with respect to spinal rod 402 due to the matingrelationship between lower portion 434 and U-shaped channel 444.

Locking cap 430 is preferably loaded in such a manner so that theradially outward extending engagement flanges 440, 442 of upper portion432 are parallel to the axis of spinal rod 402. Once upper portion 432of locking cap 430 has been properly oriented with respect to headportion 406, with radially extending flange 446 aligned with spinal rod402, upper portion 432 is rotated in a clockwise direction relative tolower portion 434 of locking cap 430 using an appropriate rotationaltool, e.g., apparatus 100. Thereupon, arcuate engagement flanges 440,442 of upper portion 432 engage corresponding engagement slots 422, 424to drive the locking cap 430 into engagement with the spinal rod 402.Once rotated into a locked position, lower portion 434 of locking cap430 is seated within recesses seating area 448 defined in the bottomsurface of upper portion 432 of locking cap 430. At such a time, theposition of head portion 406 of bone screw 404 is fixed with respect tothe longitudinal axis of spinal rod 402. As appreciated, locking cap 430rotates through approximately 45 degree arc to assume the securedposition thereof.

Turning now to FIG. 18, use of a rod apparatus 100 in conjunction withspinal stabilization system 400 will be shown and described. Initially,with reference to FIG. 18, jaw mechanism 106 of apparatus 100 is movedfrom the closed position of FIG. 5 to the opened position of FIG. 18. Inorder to open jaw assembly 106, the surgeon manipulates rack 160 in adirection “A1,” to overcome the spring bias of proximal free end 172 ofleaf spring 168 acting on planar surface of rack 160 to therebydisengage tooth 166 of lever 136 from teeth 164 of rack 160. Withproximal end 172 of lever 168 disengaged, lever 136 is automaticallypivoted about pivot pin 144 by a spring force acting in a direction “B”on recess 208 by distal free end 174 of leaf spring 168, thereby movinglever 136 away from tubular body 108 and causing movable jaw 114 topivot to the open position depicted in FIG. 18. It is appreciated thatlever 136 does not need to be spring biased to perform the operation.

Referring now to FIGS. 19A and 19B, attention is directed to mountinglocking cap 430 of spinal rod system 400 onto rod persuader 102. Rodpersuader 102 is introduced within locking shaft 104 and tubular body108, and advanced via rotation (in the direction D1) until cap spin 208projects distally beyond socket head 186 of locking shaft 106 and withinjaw mechanism 106. Locking cap 430 is loaded onto shaped tip 212 of capspin 208 with reception port 438 receiving the tip 212 in frictionalrelation therewith. Once locking cap 430 is mounted, rod persuader 102is retracted by rotating handle 206 in a counterclockwise direction towithdraw locking cap 430. It is noted that in the withdrawn position oflocking cap 430, cap body 436 is received within the arcuate recesses ofthe jaw mechanism while flanges 440, 442 of the locking cap 430 extendthrough the linear spaces defined between fixed and movable jaws 112,114. Thus, locking cap 430 is in a fixed angular position within jawmechanism 106. It is also appreciated that apparatus 100 may bepre-loaded with a locking cap 430 thereby obviating the aforementionedloading step.

With bone screw 404 secured into a vertebrae “V” and spinal rod 402positioned generally adjacent U-shaped channel 414 of bone screw 404,jaw mechanism 106 is coupled to head portion 406 of bone screw 404. Inparticular, lever 136 is moved toward handle 148 to cause pivotalmovement of movable jaw 114 to the closed position depicted in FIGS. 20and 21. In the closed position, teeth 120, 134 of fixed and movable jaws112, 114 are received within correspondingly dimensioned slots 423 ofscrew head portion 406. Jaw assembly 106 is locked onto head portion 406by the ratcheting engagement of teeth 164 of rack 160 with tooth oflever 136.

Rod persuader 102 is then rotated in a direction “D1,” wherein helicalthreads 210 of rod shaft 204 engage internal threads 196 of connectingsleeve 182 to thereby distally displace rod shaft 204. During distalmovement of rod shaft 204, locking cap 430 mounted to cap spin 286 ofrod shaft 204 engages spinal shaft 402 to drive spinal shaft 402 indirection “E1,” i.e., into U-shaped channel 414 of bone screw 404. It isappreciated that during rotation of rod shaft 204 cap spin 208 does notrotate due to the slip fit connection depicted in FIG. 13 and discussedhereinabove and the engagement of cap body 436 within the interiorsurfaces of jaws 112, 114.

Rod shaft 204 is rotated in direction “D1” until spinal shaft 402 andlocking cap 430 are fully seated within U-shaped channel 414 of bonescrew 404, as seen in FIGS. 23 and 24. Thereafter, handle assembly 180of locking shaft 104 is rotated through a 45 degree arc of rotation(relative to tubular body 108 discussed hereinabove) to causecorresponding rotation of main body 184 and socket 186 of the lockingsleeve 104. As socket 186 rotates, the keyed structure f socket head 186and cap spin 208 causes the cap spin 208 and thus locking cap 430 torotate. As seen in FIGS. 25 and 26, the rotation of locking cap 430 alsoresults in engagement flanges 440, 442 being rotated into respectivecamming slots 422, 424 of head portion 406 of bone screw 404 therebylocking spinal rod 402 in U-shaped channel 414 of bone screw 404 incompressive relation therewith.

With reference to FIGS. 27A-27C, following the fixation of locking cap430 and spinal rod 402 to bone screw 404, rod shaft 204 is rotated in adirection “D2,” opposite direction “D1,” to withdraw rod persuader 102and to disengage shaped tip 212 of cap spin 208 from locking cap 430.Jaw assembly 120 is then opened as depicted in FIG. 27C to remove theapparatus.

As seen in FIG. 28, rod persuader 100 can be used multiple times to locka spinal rod 402 to multiple bone screws 404 which are screwed intovertebrae “V” of the spinal chord.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described to beprotected. For example, it is envisioned that continued rotation of rodpersuader 102 may effectuate locking of the locking cap within the screw404 without requiring separate rotation of the handle 180 of the lockingshaft 104 by the user. In this regard, the rod persuader may bemechanically connected (through a friction fit, etc. . . . ) to thelocking shaft such that rotation of the rod persuader subsequent todriving the spinal rod within the screw head will cause rotation of thelocking shaft and thus the locking cap. It is envisioned with thisarrangement that handle 180 of the locking shaft may be engaged tosecure the locking shaft during rotating withdrawal of the rod persuader102 from the apparatus 100.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A method of securing a spinal rod to an anchoring device using a surgical instrument having a proximal end and a distal end, the method comprising: releasably attaching a locking cap to the distal end of the surgical instrument, positioning the surgical instrument to facilitate operative engagement with the spinal rod, engaging the anchoring device with the distal end of the surgical instrument, urging the spinal rod toward the anchoring device by advancing the locking cap, and securing the spinal rod to the anchoring device by using the surgical instrument to attach the locking cap to the anchoring device while capturing the spinal rod between the locking cap and the anchoring device.
 2. The method of claim 1, wherein releasably attaching the locking cap to the distal end of the surgical instrument involves frictionally fitting the locking cap onto a shaped tip portion of the distal end of the surgical instrument.
 3. The method of claim 1, wherein engaging the anchoring device with the distal end of the surgical instrument involves clamping the anchoring device with a jaw mechanism located on the distal end of the surgical instrument.
 4. The method of claim 1, wherein urging the spinal rod toward the anchoring device is accomplished by rotating a portion of the surgical instrument that is releasably attached to the locking cap to linearly advance the locking cap against the spinal rod.
 5. The method of claim 1, wherein securing the spinal rod to the anchoring device involves manipulating the surgical instrument to rotatably lock the locking cap to the anchoring device. 